You really should not fast on water alone. The lemon is an antibacterian, an alcalinizer and a source of vitamin C... it is part of the fast so is cayenne pepper.
JOint pain: Joint pain is common in severe cases of candida, so no alarm, let's just face it. What I found to be most efficient to counter joint pain is:
-cayenne pepper (a dash in your tea and a bit over your food)
-Glucosamine (glucosamine also helps with candida itself: //www.curezone.org/blogs/m.asp?f=308&i=13
-Omega 3 : fresh ground flaxseed (it turns rancid rather fast so you can grind it for the next day but to grind enough for the week is no use, it will turn bad before that, extra virgin olive oil, fish oil)
Did you keep taking the antifungal during the fast? If so, it means that it is time to rotate to another antifungal since candida is now immune to the one you have been using.